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Local and Regional Patterns in Eelgrass (Zostera marina L.) Communities Along an Upwelling-Productivity Gradient in Oregon Estuaries, USA
No full textIn this thesis, I investigate the organization of eelgrass (Zostera marina L.) and mesograzer communities across local and regional scales in three upwelling- influenced estuaries located along the Oregon coast, USA. Eelgrass ecosystems are an important source of primary production in estuarine systems, providing numerous ecosystem services, including nursery habitat for commercial fish, water quality improvement, and sediment stabilization. Community structure in eelgrass systems, i.e., the diversity, abundance, and composition of primary and secondary consumers, is influenced by a combination of local to regional scale variability in environmental and biotic factors. Thus, an important consideration in the management of these systems is to understand the organization of community structure across spatiotemporal scale and the implications for top-down (consumer) versus bottom-up (resource) control. In upwelling-influenced estuaries of the Pacific Northwest coast of the United States, eelgrass systems are exposed to latitudinal variability in oceanographic inputs, but the degree to which these regional effects versus local effects organize eelgrass community structure is poorly understood. Here I investigate the relationship between primary producers (eelgrass, ulvoid macroalgae, and epiphytes), epifauna mesograzers, and fish predators within and across three estuaries located on the Oregon Coast, USA (Netarts Bay, Yaquina Bay, and Coos Bay). Specifically, I asked: 1) What is the relative importance of local (within estuary) versus regional (across estuaries) scale patterns to eelgrass community structure (i.e., primary producers, epifaunal mesograzers, and fishes) in upwelling-influenced estuaries in Oregon?, 2) What is the potential role of regional oceanography versus trophic interactions in regulating eelgrass community structure, and is this dependent on spatial scale?, and 3) What are the management implications for eelgrass communities when regional and local scales are considered?I found that while local effects were important, regional (estuary) scale patterns strongly influenced community structure in eelgrass communities, providing support that regional oceanographic bottom-up forcing dominates eelgrass communities. Additionally, I found evidence for top-down control by the opisthobranch Phyllaplysia taylori on primary producers at one site within Netarts Bay. I suggest that eelgrass beds in these estuaries are mostly bottom-up systems, and further investigations should focus on quantifying the mechanistic relationship between mesograzers and primary producers at local to regional scales
Effect of Initial Conditions and Depressurization on Lock Exchange Flow After a Depressurized Conduction Cool-Down Event in the High Temperature Test Facility
No full textThe High Temperature Test Facility (HTTF) is an electrically heated, scaled model of a Modular High Temperature Gas Reactor (MHTGR). Five experiments were conducted to study Depressurized Conduction Cool-Down phenomena stemming from a Double-Ended Guillotine Break (DEGB). After a DEGB, the reactor pressure vessel would depressurize until the pressures are equalized between the cavity that surrounds the reactor vessel and the vessel itself. Immediately following the depressurization there would be a large density gradient between the reactor vessel, which is full of hot helium and the cavity mixture of cold air and discharged helium. This density gradient would drive lock exchange flow, where the less dense helium would travel along the top of the pipe and the denser cavity gas would intrude into the bottom of the pipe and propagate towards the lower plenum. The cavity gas would then fill the lower plenum up to the top elevation of the hot leg pipe, which would then diffuse air into the core, potentially compromising core support and fuel integrity by graphite oxidation. Lock exchange flow is a density driven mechanism that depends on the density gradient between the cavity and the pressure vessel. Gas concentrations and temperatures greatly affect density and thus affect key time characteristics of lock exchange flow. The key time characteristics to be studied in the five experiments are: the time for the gas front to arrive at the thermocouple instrumentation in the cross-duct outside the lower plenum, the time to fill the lower plenum, and the times to reach instrumented posts in the lower plenum at various heights. The time to reach the plenum will indicate the speed at which the cold dense gas front is travelling. The time to fill the lower plenum is also the time of onset of molecular diffusion. The time the gas front reaches each instrumented post will display how the cold dense gas front propagates through the plenum. The first three of five tests were conducted at ambient temperatures with initially equalized pressures between the Reactor Cavity Simulation Tank (RCST) and the Primary Pressure Vessel (PPV). The next test was a heated depressurization, and the last test was a heated test with pressures initially equalized. These three categories of tests vary initial conditions that will change lock exchange flow time characteristics
Leveraging multi-sensor time series datasets to map short- and long-term forest disturbances and drivers of change in the Colombian Andes
No full textThe spatial distribution of forest disturbance is commonly calculated using a satellite imagery-driven bi- or tri-temporal change analysis. Working in Colombia’s Cordillera de los Picachos National Natural Park – a region of consistent cloud cover and dramatic topographic relief – a change assessment with such infrequent observations cannot capture long-term trends of vegetative decline (browning) or improvement (greening) nor the drivers associated with these changes. In recognition of the importance of spatio-temporally explicit information for assessing the effects of socio-environmental change and conservation strategy implementation, I developed a rigorous assessment of vegetation change using MODIS and Landsat time-series data and the Breaks For Additive Season and Trend (BFAST) algorithm to identify the timing, trends, and locations of change as well the associated drivers.
First, I measured long-term vegetation trends from 2001-2015 using a Moderate Resolution Imaging Spectroradiometer (MODIS)-based 250m resolution Multi-Angle Implementation of Atmospheric Correction (MAIAC) time-series, and mapped short-term disturbances using all available Landsat images (149 dates from Landsat 5, 7, and 8). BFAST trends based on MAIAC data indicate a net greening in 6% of the park, with a net browning trend of 2.5% in the 10km-wide region surrounding the park. I also identified a 12,500 ha area within Picachos (4% of the park’s total area) that experienced a consecutive vegetative decline or browning during every year of study, a result corroborated with a BFAST Monitor assessment using finer 30m resolution Landsat data. With Landsat, I recorded 12,642 ha (±1440) of disturbed forest within the park at high spatial and temporal accuracy. Spatially, Landsat results had user’s and producer’s accuracies of 0.95±0.02 and 0.83±0.18, respectively. Temporally, a TimeSync-supported temporal validation assessment showed that 75% of Landsat-detected dates of disturbance events were accurate within ± 6 months.
With disturbances identified, I characterized disturbances within Picachos’ southeastern foothills and associated drivers using a set of metrics related to the spectral, pattern and trend properties of disturbance patches derived from Landsat time-series data (1996-2015). A training dataset was initially developed to identify drivers of disturbances using Corine Land Cover maps and high-resolution imagery. A Random Forests classifier was used to attribute disturbances to specific drivers of forest cover change: conversion to pasture, conversion to subsistence agriculture, and non-stand replacing disturbance (i.e., thinning). Attribution of changes had high accuracy at patch and area levels with 1-5% commission and 2-14% omission errors, respectively, for regions that were converted to pasture or experienced thinning. Lower agreement was found for agricultural conversion with 43% omission and 9% commission errors.
I found that conversion to pasture is the main cause of forest cover loss within Picachos at 9901 ha (±72) corresponding to 14.7% of Picachos’ foothills, and that subtle forest alteration contributed to 1327 ha (±92) of forest degradation. Recognizing the diversity of pressures facing conservation strategy implementation in the region, these results have direct relevance for anticipating future land use pressures within Colombia, as well as across similar regions in the Andes-Amazon transition area. Indeed, since these results reveal the possibility to uncover historical disturbances related to human-incursion in protected landscapes, the methods are well suited to enhancing landscape planning particularly where biodiversity richness is quickly diminishing due to anthropogenic presence
Breeding, Production, and Morphophysiology Among Cytotypes of Common and Portuguese Cherrylaurel
No full textThe common cherrylaurel (Prunus laurocerasus) and Portuguese cherrylaurel (P. lusitanica) are economically important landscape shrubs across the United States. To gain a better understanding of physiology and morphology in these higher level polyploids (P. lusitanica, 2n = 8x; P. laurocerasus, 2n =22x), a variety of breeding experiments were performed. The long-term goal of these experiments was to lay the ground-work for the creation of a sterile, shothole disease resistant cherrylaurel, while maintaining its desirable ornamental features.
In attempt to narrow the gap in ploidy level between these two species, the chromosome number of P. lusitanica was doubled using colchicine and oryzalin, and differences in cytotypes were observed. This was performed with the hope of performing interspecific hybridization and introgression of shothole disease resistance in to P. laurocerasus. The most effective method was found to be oryzalin at a rate
of 125 μM, and induced polyploids were shorter, had thicker leaves, and larger but fewer stomata.
Preliminary research was performed to germinate immature P. lusitanica seed, in vitro, to develop a putative embryo rescue medium for use in this interspecific hybridization. The most significant factor in the media for successful germination was sucrose, with 30 g·L⁻¹ of sucrose media germinating significantly more seed than 60 g·L⁻¹. Also, germination only occurred at 12 weeks after pollination, with no germination at 6 and 9 weeks regardless of cold-stratification.
Existing chromosome doubled cytotypes of P. laurocerasus were compared to the standard ploidy cytotype. Differences in vegetative propagation were observed and reported in the Schipkaensis cultivar. Chromosome doubled P. laurocerasus ‘Schipkaensis’ rooted at an equivalent percentage, had equivalently long roots, and had fewer roots per cutting. Deceased number of roots produced no apparent detrimental effects in propagation success.
In cytotypes of the Otto Luyken cultivar, numerous morphological and physiological were made. Chromosome double forms were generally shorter, smaller in width and conical volume, and had larger but fewer stomata. The also had increased stomatal conductance and transpiration, with decreased water-use efficiency. Size and biomass observations were used to estimate carbon fixation, and chromosome doubled Otto Luyken cultivars were estimated to fix significantly less carbon
SMR full-power scaling analysis and numerical simulation for nuclear hybrid energy system testing
No full textA scaling analysis of the Oregon State University (OSU) - Multi-Application Small Light Water Reactor (MASLWR) system has been developed, and an existing RELAP5-3D model of the facility was improved. The purpose of this study is to support the research of hybrid energy systems, being led by Idaho National Laboratory (INL). Hybrid energy systems have recently become a point of interest for their ability to combine nuclear and non-nuclear clean power generation, while also providing energy storage and industrial production capabilities. Hybrid Energy Systems could well utilize small modular reactors (SMRs). For this study, the specific requirement is a RELAP5-3D model of the NuScale design. The OSU-MASLWR system modeled an older version of the NuScale design, so the RELAP model is based on that facility. However, MASLWR was not scaled for the types of testing that INL requires, so a new set of scaling parameters was developed. The RELAP model was benchmarked against IAEA data from an International Collaborative Standard Problem study performed at MASLWR in 2010. This work shows that the RELAP model agrees well with test data, and is therefore suitable for simulating the performance of the MASLWR system for nuclear hybrid energy system testing
Synthesis, surface treatment, and characterization of copper indium sulfide quantum dots
No full textThe need for less toxic quantum dots (QDs) has led to a significant number of investigations related to copper indium sulfide (CIS) QDs. Lower toxicity and broad band absorbance width makes CIS QDs appealing for light emitting diodes (LEDs), lasers, sensors, bio-imaging, solar cells, and computing. The optical and electronic properties of CIS QDs can be modified by varying their size, composition, and surface characteristics. CIS QDs with 1:1, 1:2, and 1:5 Cu:In ratios were synthesized, and their optical and chemical properties were investigated using UV-Vis, spectrofluorometry, Raman, and Fourier transform infrared (FTIR) spectrometry. The composition of the as synthesized CIS QDs were determined by energy dispersive spectroscopy (EDS), and their size, shape, and crystal structure were determined by using high resolution transmission electron microscope (HR-TEM). The as synthesized samples had compositions similar to the reaction precursors. Decreasing the QDs Cu:In ratio from 1:1 to 1:2 and 1:5 resulted in a blue shifted emission from 664 nm to 640 nm and 638 nm, respectively. The excitonic peak in the absorbance spectra shifted to higher energy
with decreasing the Cu:In ratio. The 1:2 Cu:In ratio resulted in the highest photoluminescence quantum yield (PLQY), where the PLQY increases with Cu vacancies up to the 1:2 Cu:In ratio QDs and decreases afterward due to reabsorption. The as synthesize CIS QDs core surface was treated with an organic super acid to improve the surface states. The treated CIS core QDs PLQY increased by more than 50%, compared to the untreated CIS core QDs, without affecting the optical properties. The organic super acid treated CIS QDs core was further passivated with ZnS and the resulting hybrid surface passivated CIS/ZnS QDs showed a PLQY improvement over 66%. No significant change in size, shape, composition, emission band, and absorption properties were observed for organic super acid treated CIS QDs. The super acid improved the PLQY without significantly affecting optical, structural, and chemical properties of CIS QDs
Use of herbal feed additives in poultry feeding
No full textThe use of an antibiotic as a growth promoter (AGP) began in the 1940’s with the discovery of growth responses from Streptomyces aureofaciens in the monogastric diet. However, resistance and residue problems have increased the negative consumer perception of growth promoting antibiotic use in animal diets. Although no direct link between antibiotic resistance in animals and succeeding antibiotic resistance in humans, there has been increased interest and push to find alternatives to AGPs.
Many different types of alternatives such as pre/probiotics, phytogenic compounds (e.g. herbs, and essential oils), enzymes and organic acids are being studied as AGP alternatives. Herbs are one of the four subgroups of the phytogenic classification. Plant based products contain plant secondary metabolites or phytochemicals which are effective as feed additives. Previous studies have found positive results with inclusion of phytogenic feed additives in poultry diets. Two experiments were carried out to test the effectiveness of herbal supplements (Superliv® Concentrate Premix (broiler) and AV/HLP/16 (layer)) on production performance, hindgut bacterial proportions of microbes, liver and muscle tissue lipid composition, and nutrient efficiency in broilers and on production performance, egg quality, egg and liver fatty acid composition, lipid stability, and hen serum lipids in laying hens.
In experiment one, effect of the herbal blend (Superliv® Concentrate Premix) and different levels of nutrient density in the diet of meat-type chickens was investigated. A total of 120, one day-old Cobb broiler chicks were fed diets varying in metabolizable energy (ME) (Control, 2.5% reduced ME, 5% reduced ME) with and without Superliv® Concentrate Premix herbal blend. Body weight was the lowest for birds receiving the 5.0% Low Energy diet at the prestarter, grower and finisher phase (p≤0.05). Feeding 2.5% Low Energy diet had no effect on final body weight (p>0.05). No effect of energy level of the diet on total feed conversion ratio (FCR) was observed (p>0.05). Gizzard weight was lowest in Control birds (p≤0.05). The Control diet broilers had significantly higher liver total lipid levels than the 2.5% and the 5.0% reduced energy diets (p≤0.05). The apparent total tract retention of fat was increased in birds fed 2.5% and 5.0% Low Energy diets (p≤0.05). Fecal dry matter (%) was lowest for birds fed 5.0% Low Energy (p≤0.05). Energy level in the diet did not impact total relative proportions of the Lactobacillus, Bifidobacterium and Salmonella in the cecum (p>0.05).
With respect to herbal supplementation in the diet, there was an increase in relative fat pad weight in birds receiving the supplement (p≤0.05). Total lipids was higher in the thigh muscle of birds fed the herbal supplement (p≤0.05). A significant increase in the relative proportion of Lactobacillus was observed in birds fed a diet containing the herbal supplement (p≤0.05). Fecal dry matter (%) was reduced in the birds receiving the supplement (p≤0.05). No effect of herb was found on the production performance indicators (FCR, body weight) or the apparent total tract retention of energy or fat (p>0.05).
In experiment two, the inclusion of an herbal blend formulated for layers (AV/HLP/16) at different levels in the diet was investigated. A total of 96 brown layers (age 27 weeks) were kept in individual cages and fed a commercially formulated diet with either 0% (Control), 0.1% (Diet 1), 0.15% (Diet 2) or 0.2% (Diet 3) AV/HLP/16 supplement for four months. Egg mass and egg production were highest in hens receiving Diet 3 (p≤0.05). Feed consumption did not differ significantly among the treatments (p>0.05). FCR was lowest for Diet 3 but there was only a trend for significance (p>0.05). Shell, yolk and albumen weight (%) did not differ between diets (p>0.05). Haugh unit and yolk index values were highest in birds fed Diet 3 (p≤0.05). Lipid oxidation products in the liver were highest for Diet 1 and Diet 3 but there was only a trend for significance (p>0.05). Egg lipid oxidation products were highest in Diet 2 (p≤0.05). Total lipids (%) in the liver was lowest in Diet 2 and Diet 3 (p≤0.05). There was no difference in yolk total lipids (%) (p>0.05). There were differences in individual yolk fatty acids. There was a significant decrease in stearic acid and arachidonic acid in egg yolks from Diet 3 (p≤0.05). Linoleic acid was reduced in supplemented diets (p≤0.05). Egg lipid content decreased as the hen aged (p≤0.05). No effect of diet on egg cholesterol or hen serum triglycerides was observed (p>0.05).
Overall, Superliv® Concentrate Premix herbal supplementation in the 2.5% Low Energy broiler diet maintained production performance while enhancing the beneficial bacteria in the hindgut when compared to the Control diet. In the layer, AV/HLP/16 herbal supplementation at 0.2% increased egg weight and improved production performance
Fighting to Cooperate: Litigation, Collaboration, and Water Management in the Upper Deschutes River Basin
No full textCommunities across the American West face new challenges in water management: historical management structures devised to prioritize economic uses, predominantly agriculture, are being tasked with adapting to address growing and changing populations, unaddressed species and ecosystem needs, and climatic changes. Scholars in the field of collaborative governance posit that collaborative processes may generate more innovative and flexible solutions better suited to resolving modern environmental problems, such as water management, than traditional regulatory approaches. However, there is a debate within this field about how collaboration and regulatory enforcement in the form of litigation may interact: does litigation destroy collaborative governance efforts or does litigation serve as a mechanism to facilitate collaboration? This thesis explores this question through a qualitative case study of the Upper Deschutes River Basin in Oregon, which provides an example of a community wrestling with the changing context of water management in the American West. Stakeholders, representing the diverse water interests in the basin, began two collaborative processes, the Upper Deschutes River Basin Study and the Deschutes Basin Habitat Conservation Plan, to lay the foundation for a new water management regime to address this changing context. However, a participant in these processes was concerned that they were not progressing and filed a lawsuit under the citizen suit provision of the Endangered Species Act seeking to mandate immediate flow changes in the Upper Deschutes River to protect the federally threated Oregon spotted frog. The results of this research, derived from semi-structured interviews with participants in the processes and observation and document analysis techniques, reveal that in this case the litigation, while having negative effects, did not destroy the collaborative processes; rather the litigation served as a mechanism to facilitate the collaborative processes by increasing incentives for the powerful to commit to making change within the collaborative processes and creating an assurance mechanism for the weak that their interests will be met in the collaboratives. The results of this research also illustrate that while the litigation was seen to help facilitate the collaborative processes, ultimately collaboration is perceived as the best method for developing a new water management regime in the basin
Why women endorse ambivalent sexism : risks of young women's enjoyment of sexualization and the protective powers of feminism
No full textHostile sexism (HS) is an antagonistic attitude towards women; benevolent sexism (BS) is a positive attitude towards women that is sexist in terms of viewing women in restricted roles. HS and BS held simultaneously is defined as ambivalent sexism (AS). Despite negative outcomes associated with AS, BS, and HS, women on average report endorsing AS, BS, and HS. Our study examined the extent to which viewing and describing pictures of female celebrities in stereotypically feminine and counter-stereotypical forms influences young adult women’s endorsement of AS, BS, and HS. It was predicted that highly-feminine images would increase participants’ AS, BS, and HS while unfeminine images would decrease participants’ AS, BS, and HS. Participants were randomly assigned to view and describe a series of highly-feminine, unfeminine, or control (natural scenery) photos and complete pretest and posttest Ambivalent Sexism Inventory (ASI) measurements. Results indicated that women’s endorsement of AS, BS, and HS did not change significantly between any of the photo conditions, suggesting viewing and describing images of female celebrities did not impact women’s endorsement of AS, BS, or HS. However, we were able to identify psychological entitlement and enjoyment of sexualization as positively related constructs, and feminist identity as a negatively related construct to women’s endorsement of AS, BS, and HS. The importance and implications of identifying risk and protective factors on women’s endorsement of AS, BS, and HS are discussed
Event detection with forward-backward recurrent neural networks
No full textAutomatic event extraction from natural text is an important and challenging task for natural language understanding. Traditional event detection methods heavily rely on manually engineered rich features. Recent deep learning approaches alleviate this problem by automatic feature engineering. But such efforts, like tradition methods, have so far only focused on single-token event mentions, whereas in practice events can also be described with a phrase. In this thesis, we introduce and apply forward-backward recurrent neural networks (FBRNNs) to detect events that can be either words or phrases. Experimental results demonstrate that FBRNN is competitive with the state-of-the-art methods on the ACE 2005 and the Rich ERE 2015 event detection tasks.Keywords: Deep Learning, Event Detectio